1. Field of the Invention
The present invention relates to an airborne particulate analyzer. More specifically, the present invention relates to a microfabricated device for selectively removing and analyzing airborne particulates from an air stream.
2. Related Art
A number of techniques are presently used to separate airborne particulate matter from an air stream in order to determine the size and possibly type and quantity of particulates in the air stream, and to filter the air stream. These particulates can include environmental pollution and pathogens, such as bacteria and viruses.
Current approaches to separating airborne particulate matter involve using large devices, some of which require a radio-active ionization source. This is particularly true for devices used for separating particulates smaller than 100 nm in size. These devices typically grow particulates to an optimal size after separation to facilitate optical counting. Handheld devices do not exist that are capable of separating and counting particulates smaller than 100 nm. Detection of particulates smaller than 100 nm is advantageous because it includes airborne pathogens such as viruses.
The techniques used to detect particulates optically are limited to discrete size bins. These devices are only capable of detecting specific size particulates (i.e. 100 nm, 300 nm, 500 nm, etc). They cannot, however, be re-configured to give values for 150 nm, 180 nm, etc. This is because a specific wavelength that is equivalent to the particulate size is required for their detection. In order to count all particulates, a laser source or array of laser sources to give a continuous wavelength spectrum is required. This is prohibitively expensive.
Current portable devices are not able to determine the composition of the particulates, and hence provide little benefit in detecting chemical and/or biological agents. On the other hand, devices which are able to detect these chemical and biological agents are typically laboratory devices, which are unsuitable for field work.
The size of current particulate analyzers that are able to detect particulates smaller than 100 nm precludes using them in portable devices, and the substantial price of these particulate analyzers makes ubiquitous positioning within an urban area prohibitively expensive.
Hence, what is needed is a portable apparatus, which can effectively size and count particulates smaller than 100 nm in an air stream without the drawbacks cited above. Determining the actual size of the particulates is advantageous because it can possibly lead to determining the source of the particulates.